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Date: Mon, 28 Nov 2022 06:30:33 +0300
From: "Konstantin Meskhidze (A)" <konstantin.meskhidze@...wei.com>
To: Mickaël Salaün <mic@...ikod.net>
CC: <willemdebruijn.kernel@...il.com>, <gnoack3000@...il.com>,
<linux-security-module@...r.kernel.org>, <netdev@...r.kernel.org>,
<netfilter-devel@...r.kernel.org>, <artem.kuzin@...wei.com>
Subject: Re: [PATCH v8 05/12] landlock: Refactor unmask_layers() and
init_layer_masks()
11/17/2022 9:42 PM, Mickaël Salaün пишет:
>
> On 21/10/2022 17:26, Konstantin Meskhidze wrote:
>> Adds new key_type argument to init_layer_masks() helper.
>
> Add a new key_type argument to the…
>
>> Adds masks_array_size argument to unmask_layers() helper.
>
> Add a masks_array_size argument to the…
>
>
> The name of these helpers need to be prefixed with "landlock_".
>
>
Thanks. Will be Fixed.
>> These modifications support implementing new rule types in the next
>> Landlock versions.
>>
>> Co-developed-by: Mickaël Salaün <mic@...ikod.net>
>
> Signed-off-by: Mickaël Salaün <mic@...ikod.net>
Got it.
>
>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
>> ---
>>
>> Changes since v7:
>> * Refactors commit message, adds a co-developer.
>> * Minor fixes.
>>
>> Changes since v6:
>> * Removes masks_size attribute from init_layer_masks().
>> * Refactors init_layer_masks() with new landlock_key_type.
>>
>> Changes since v5:
>> * Splits commit.
>> * Formats code with clang-format-14.
>>
>> Changes since v4:
>> * Refactors init_layer_masks(), get_handled_accesses()
>> and unmask_layers() functions to support multiple rule types.
>> * Refactors landlock_get_fs_access_mask() function with
>> LANDLOCK_MASK_ACCESS_FS mask.
>>
>> Changes since v3:
>> * Splits commit.
>> * Refactors landlock_unmask_layers functions.
>>
>> ---
>> security/landlock/fs.c | 36 ++++++++++++++++++-------------
>> security/landlock/ruleset.c | 42 ++++++++++++++++++++++++++-----------
>> security/landlock/ruleset.h | 11 +++++-----
>> 3 files changed, 58 insertions(+), 31 deletions(-)
>>
>> diff --git a/security/landlock/fs.c b/security/landlock/fs.c
>> index 240e42a8f788..fe76a11483f8 100644
>> --- a/security/landlock/fs.c
>> +++ b/security/landlock/fs.c
>> @@ -435,16 +435,20 @@ static bool is_access_to_paths_allowed(
>> if (unlikely(dentry_child1)) {
>> unmask_layers(find_rule(domain, dentry_child1),
>> init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
>> - &_layer_masks_child1),
>> - &_layer_masks_child1);
>> + &_layer_masks_child1,
>> + LANDLOCK_KEY_INODE),
>> + &_layer_masks_child1,
>> + ARRAY_SIZE(_layer_masks_child1));
>> layer_masks_child1 = &_layer_masks_child1;
>> child1_is_directory = d_is_dir(dentry_child1);
>> }
>> if (unlikely(dentry_child2)) {
>> unmask_layers(find_rule(domain, dentry_child2),
>> init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
>> - &_layer_masks_child2),
>> - &_layer_masks_child2);
>> + &_layer_masks_child2,
>> + LANDLOCK_KEY_INODE),
>> + &_layer_masks_child2,
>> + ARRAY_SIZE(_layer_masks_child2));
>> layer_masks_child2 = &_layer_masks_child2;
>> child2_is_directory = d_is_dir(dentry_child2);
>> }
>> @@ -496,15 +500,16 @@ static bool is_access_to_paths_allowed(
>> }
>>
>> rule = find_rule(domain, walker_path.dentry);
>> - allowed_parent1 = unmask_layers(rule, access_masked_parent1,
>> - layer_masks_parent1);
>> - allowed_parent2 = unmask_layers(rule, access_masked_parent2,
>> - layer_masks_parent2);
>> + allowed_parent1 = unmask_layers(
>> + rule, access_masked_parent1, layer_masks_parent1,
>> + ARRAY_SIZE(*layer_masks_parent1));
>> + allowed_parent2 = unmask_layers(
>> + rule, access_masked_parent2, layer_masks_parent2,
>> + ARRAY_SIZE(*layer_masks_parent2));
>>
>> /* Stops when a rule from each layer grants access. */
>> if (allowed_parent1 && allowed_parent2)
>> break;
>> -
>> jump_up:
>> if (walker_path.dentry == walker_path.mnt->mnt_root) {
>> if (follow_up(&walker_path)) {
>> @@ -543,7 +548,8 @@ static inline int check_access_path(const struct landlock_ruleset *const domain,
>> {
>> layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {};
>>
>> - access_request = init_layer_masks(domain, access_request, &layer_masks);
>> + access_request = init_layer_masks(domain, access_request, &layer_masks,
>> + LANDLOCK_KEY_INODE);
>> if (is_access_to_paths_allowed(domain, path, access_request,
>> &layer_masks, NULL, 0, NULL, NULL))
>> return 0;
>> @@ -630,7 +636,7 @@ static bool collect_domain_accesses(
>> return true;
>>
>> access_dom = init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
>> - layer_masks_dom);
>> + layer_masks_dom, LANDLOCK_KEY_INODE);
>>
>> dget(dir);
>> while (true) {
>> @@ -638,7 +644,8 @@ static bool collect_domain_accesses(
>>
>> /* Gets all layers allowing all domain accesses. */
>> if (unmask_layers(find_rule(domain, dir), access_dom,
>> - layer_masks_dom)) {
>> + layer_masks_dom,
>> + ARRAY_SIZE(*layer_masks_dom))) {
>> /*
>> * Stops when all handled accesses are allowed by at
>> * least one rule in each layer.
>> @@ -754,7 +761,7 @@ static int current_check_refer_path(struct dentry *const old_dentry,
>> */
>> access_request_parent1 = init_layer_masks(
>> dom, access_request_parent1 | access_request_parent2,
>> - &layer_masks_parent1);
>> + &layer_masks_parent1, LANDLOCK_KEY_INODE);
>> if (is_access_to_paths_allowed(
>> dom, new_dir, access_request_parent1,
>> &layer_masks_parent1, NULL, 0, NULL, NULL))
>> @@ -1131,7 +1138,8 @@ static int hook_file_open(struct file *const file)
>>
>> if (is_access_to_paths_allowed(
>> dom, &file->f_path,
>> - init_layer_masks(dom, full_access_request, &layer_masks),
>> + init_layer_masks(dom, full_access_request, &layer_masks,
>> + LANDLOCK_KEY_INODE),
>> &layer_masks, NULL, 0, NULL, NULL)) {
>> allowed_access = full_access_request;
>> } else {
>> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
>> index 02ab14439c43..c7cf54ba4f6d 100644
>> --- a/security/landlock/ruleset.c
>> +++ b/security/landlock/ruleset.c
>> @@ -576,13 +576,15 @@ landlock_find_rule(const struct landlock_ruleset *const ruleset,
>> /*
>> * @layer_masks is read and may be updated according to the access request and
>> * the matching rule.
>> + * @masks_array_size must be equal to ARRAY_SIZE(*layer_masks).
>> *
>> * Returns true if the request is allowed (i.e. relevant layer masks for the
>> * request are empty).
>> */
>> bool unmask_layers(const struct landlock_rule *const rule,
>> const access_mask_t access_request,
>> - layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS])
>> + layer_mask_t (*const layer_masks)[],
>> + const size_t masks_array_size)
>> {
>> size_t layer_level;
>>
>> @@ -614,8 +616,7 @@ bool unmask_layers(const struct landlock_rule *const rule,
>> * requested access.
>> */
>> is_empty = true;
>> - for_each_set_bit(access_bit, &access_req,
>> - ARRAY_SIZE(*layer_masks)) {
>> + for_each_set_bit(access_bit, &access_req, masks_array_size) {
>> if (layer->access & BIT_ULL(access_bit))
>> (*layer_masks)[access_bit] &= ~layer_bit;
>> is_empty = is_empty && !(*layer_masks)[access_bit];
>> @@ -626,6 +627,10 @@ bool unmask_layers(const struct landlock_rule *const rule,
>> return false;
>> }
>>
>> +typedef access_mask_t
>> +get_access_mask_t(const struct landlock_ruleset *const ruleset,
>> + const u16 layer_level);
>> +
>> /**
>> * init_layer_masks - Initialize layer masks from an access request
>> *
>> @@ -635,19 +640,33 @@ bool unmask_layers(const struct landlock_rule *const rule,
>> * @domain: The domain that defines the current restrictions.
>> * @access_request: The requested access rights to check.
>> * @layer_masks: The layer masks to populate.
>> + * @key_type: The key type to switch between access masks of different types.
>> *
>> * Returns: An access mask where each access right bit is set which is handled
>> * in any of the active layers in @domain.
>> */
>> -access_mask_t
>> -init_layer_masks(const struct landlock_ruleset *const domain,
>> - const access_mask_t access_request,
>> - layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS])
>> +access_mask_t init_layer_masks(const struct landlock_ruleset *const domain,
>> + const access_mask_t access_request,
>> + layer_mask_t (*const layer_masks)[],
>> + const enum landlock_key_type key_type)
>> {
>> access_mask_t handled_accesses = 0;
>> - size_t layer_level;
>> + size_t layer_level, num_access;
>> + get_access_mask_t *get_access_mask;
>> +
>> + switch (key_type) {
>> + case LANDLOCK_KEY_INODE:
>> + get_access_mask = landlock_get_fs_access_mask;
>> + num_access = LANDLOCK_NUM_ACCESS_FS;
>> + break;
>> + default:
>> + WARN_ON_ONCE(1);
>> + return 0;
>> + }
>> +
>> + memset(layer_masks, 0,
>> + array_size(sizeof((*layer_masks)[0]), num_access));
>>
>> - memset(layer_masks, 0, sizeof(*layer_masks));
>> /* An empty access request can happen because of O_WRONLY | O_RDWR. */
>> if (!access_request)
>> return 0;
>> @@ -657,14 +676,13 @@ init_layer_masks(const struct landlock_ruleset *const domain,
>> const unsigned long access_req = access_request;
>> unsigned long access_bit;
>>
>> - for_each_set_bit(access_bit, &access_req,
>> - ARRAY_SIZE(*layer_masks)) {
>> + for_each_set_bit(access_bit, &access_req, num_access) {
>> /*
>> * Artificially handles all initially denied by default
>> * access rights.
>> */
>> if (BIT_ULL(access_bit) &
>> - (landlock_get_fs_access_mask(domain, layer_level) |
>> + (get_access_mask(domain, layer_level) |
>> ACCESS_INITIALLY_DENIED)) {
>> (*layer_masks)[access_bit] |=
>> BIT_ULL(layer_level);
>> diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
>> index 50baff4fcbb4..d9eb79ea9a89 100644
>> --- a/security/landlock/ruleset.h
>> +++ b/security/landlock/ruleset.h
>> @@ -259,11 +259,12 @@ landlock_get_fs_access_mask(const struct landlock_ruleset *const ruleset,
>>
>> bool unmask_layers(const struct landlock_rule *const rule,
>> const access_mask_t access_request,
>> - layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]);
>> + layer_mask_t (*const layer_masks)[],
>> + const size_t masks_array_size);
>>
>> -access_mask_t
>> -init_layer_masks(const struct landlock_ruleset *const domain,
>> - const access_mask_t access_request,
>> - layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]);
>> +access_mask_t init_layer_masks(const struct landlock_ruleset *const domain,
>> + const access_mask_t access_request,
>> + layer_mask_t (*const layer_masks)[],
>> + const enum landlock_key_type key_type);
>>
>> #endif /* _SECURITY_LANDLOCK_RULESET_H */
>> --
>> 2.25.1
>>
> .
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